Improvement in the manufacture of artificial hydraulic or portland cement



adapted.

UNITED STATES PATENT Our-Ion.

CALVIN BROWN, or MARE ISLAND, CALIFORNIA.

IMPROVEMENT IN THE MANUFACTUREOF ARIIFICIAL'HYDRAULIC 0R PORTLAND CEMENT.

Specification forming part of Letters Patent No. 222,004, dated November 25, 1879; application filed September 30, 1879.

To all whom it may concern:

Be it known that I, CALVIN BROWN, of Mare Island, in the county of Solano and State of California, have invented a new and useful Process in the Manufacture of Artificial Hydraulic or Portland Cement, which process is fully set forth in the following specification.

. This invention relates to that class of processes employed for forming or molding the mixed raw materials constitntin g said cements before their calcination; and it consists in giving spherical or cylindrical shapes to the portions or pieces into which the said raw materials are required to be divided before placing them in the kiln for calcination.

In carrying out my invention I make use of ordinary pug-mills provided with circular discharging-orifices, in the center of which cylindrical cores or dies are placed, so that the mixed raw materials, in a proper plastic state, may exude from theseorifices in the form of hollow cylinders of about three and ahalf inches in exterior diameter, the hole or bore formed by the core or die being about one and a half inch in diameter. .The material thus exuding in the form described is divided into pieces of about three and a half inches in length by means of any suitable cutting apparatus. In the case of balls or spherically-shaped figures, pug-mills are similarly used, being provided or connected with an apparatus for producing the required forms with an axial bore or hole of about one andahalf inch in diameter, the exterior diameter of the ball being about three and a half inches. As in the case of the cylinders, the bore of the ball extends entirely through. Upon the formation of the cylinders or balls they are placed in a drying apparatus for desiccation before being placed'in the kiln.

An indispensable requirement in the manufacture of artificial hydraulic cement is exact calcination, for which my process is peculiarly This operation affects both its quality and cheapness. Its proper management is involved in the precision in which the preliminary details of mixing, shaping, and drying theraw materials are. performed, and finally in charging the kiln. Perfect calcination demands a certain degree and duration of heat, acting equally upon the contents of the kiln. With these conditions of heat is necessarily involved the proper adaptation of the mass to be calcined. If this be divided in pieces of nearly equal thickness and circular shapes, precluding surface contact and admitting of numerous interstices when charged in the kiln, thus allowing the free circulation of heat, a uniform calcination will be the result. If, on the contrary, the mass be in pieces of varying thickness, or in shapes that admit of surface contact, it is evident that the required degree of heat cannot act in the uniform manner desired; its free circulation cannot be established, in consequence of the close contact of the pieces, which obstructs the draft; the conduction of the heat will be unequal and the mass will be unequally calcined, and a portion only will be converted into a good cement clinker, as it is termed, and fit for use, while other portions will be overburned and thus wasted, and still another portion will be under-burned and will require a further calcination for its proper conversion to cement.

I am aware that solid cylinders and solid balls of the raw materials have been used in the manufacture of artificial hydraulic cement, but not perforated ones, before my own use of them.

I am also aware that in what is known as the dry system of making such cement the raw materials are molded into hollow rectangular prisms. In this case the prisms, when dried, are, like ordinary clay bricks, carefully piled in the kiln in such a manner as may admit of the circulation and conduction of the heat as perfectly as the system will allow--an operation which requires much labor. It is obvious, however, that with forms of flat surfaces there must be a far greater contact of the materials, and consequent obstruction of draft and conduction of heat, than where the forms are circular. In what is known as the wet system the prepared materials, after drying, enter the kilns in shapeless and various-sized pieces, and with such a tendency of surface contact that the mass can be burned only by charging the kilns with alternate layers of fuel and thin strata of the raw materialan operation which equally requires much labor, while the resulting calcination is irregular, and is frequently attended with the loss and waste of the whole contents of the kiln.

In my inyention the balls or the cylinders ment into hollow cylindrical portions or perare simply thrown with the fuel into the kiln forated spherical balls, or their equivalents,

Without the necessity of piling or elaborate for the purpose of a more economical and unispreading of the layers, thus saving the time form caloination substantially as described.

' and labor involved in the use of other forms. CALVIN BROWN.

I claim as my in'vention The process of molding or forming the Witnesses: mixed raw materials required for the manu- J. H. HOADLEY, faoture of artificial hydraulic or Portland ce- FRANK E. BROWN. 

